package com.htdata.iiot.tools;

import java.io.IOException;
import java.math.BigInteger;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

import org.apache.commons.codec.binary.Base64;

/**
 * Created by liuqiang on 2016/11/16.
 */
public class SecurityHelper {
    private final static String DES = "DES";

    private static String desKey = "qJcXqjPUX0Zznaz6";


    /**
     * md5 哈希
     *
     * @param data
     * @return
     * @throws NoSuchAlgorithmException
     */
    public static String md5(String data) throws NoSuchAlgorithmException {
        MessageDigest m = MessageDigest.getInstance("MD5");
        m.update(data.getBytes(Charset.forName("UTF-8")));
        byte[] digest = m.digest();
        BigInteger bigInt = new BigInteger(1, digest);
        String result = bigInt.toString(16);
        if (result.length() < 32) {
            StringBuffer buffer = new StringBuffer(result);
            while (buffer.length() < 32) {
                buffer.insert(0, '0');
            }

            result = buffer.toString();
        }

        return result;
    }

    /**
     * 使用配置des.key进行加密
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static String encrypt(String data) throws Exception {
        return encrypt(data, desKey);
    }

    /**
     * 使用配置des.key进行解密
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static String decrypt(String data) throws Exception {
        return decrypt(data, desKey);
    }

    /**
     * Description 根据键值进行加密
     *
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws Exception
     */
    public static String encrypt(String data, String key) throws Exception {
        byte[] bt = encrypt(data.getBytes(Charset.forName("UTF-8")), key.getBytes(Charset.forName("UTF-8")));
        String result = Base64.encodeBase64String(bt);
        return result;
    }

    /**
     * Description 根据键值进行解密
     *
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws IOException
     * @throws Exception
     */
    public static String decrypt(String data, String key) throws Exception {
        if (data == null)
            return null;

        byte[] buf = Base64.decodeBase64(data);
        byte[] bt = decrypt(buf, key.getBytes(Charset.forName("UTF-8")));
        return new String(bt, Charset.forName("UTF-8"));
    }

    /**
     * Description 根据键值进行加密
     *
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws Exception
     */
    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
        // 生成一个可信任的随机数源
        SecureRandom sr = new SecureRandom();

        // 从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);

        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey secureKey = keyFactory.generateSecret(dks);

        // Cipher对象实际完成加密操作
        Cipher cipher = Cipher.getInstance(DES);

        // 用密钥初始化Cipher对象
        cipher.init(Cipher.ENCRYPT_MODE, secureKey, sr);

        return cipher.doFinal(data);
    }


    /**
     * Description 根据键值进行解密
     *
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws Exception
     */
    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
        // 生成一个可信任的随机数源
        SecureRandom sr = new SecureRandom();

        // 从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);

        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey secureKey = keyFactory.generateSecret(dks);

        // Cipher对象实际完成解密操作
        Cipher cipher = Cipher.getInstance(DES);

        // 用密钥初始化Cipher对象
        cipher.init(Cipher.DECRYPT_MODE, secureKey, sr);

        return cipher.doFinal(data);
    }
}
